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Hydrothermal processed heterogeneous MoS2 assisted charge transport in dye sensitized solar cells
摘要： Photovoltaic performance in dye sensitized solar cells (DSSCs) was improved by incorporating hydrothermal processed molybdenum disulfide (MoS2) into the bulk of titanium dioxide (TiO2) nanoparticle film. MoS2 exhibits a heterogeneous morphology comprising randomly distributed clustered nanoparticles and one dimensional nano-needles. The heterogeneous MoS2 was examined by X-ray photoelectron spectroscopy to study Mo 3d and S 2p peaks. Transmission electron microscopic studies on the heterogeneous MoS2 assert the presence of multilayers which further confirmed by UV–visible optical absorption spectroscopy showed absence of band-edge excitonic peaks at 612 nm and 674 nm. DSSCs show 17% enhancement in performance for 0.09 wt% of heterogeneous MoS2 incorporated TiO2 nanoparticle film compared to reference DSSC fabricated using only TiO2. Further changes in performance was examined by varying the concentration of MoS2 in TiO2 and observed that there is an optimum value to facilitate photo-generated charge transport kinetics in TiO2. The heterogeneous nature of MoS2 effectively acquired photo-electrons from TiO2 due to the presence of conduction band edge few meV below than that of in TiO2 and helps improving the performance.
关键词： TiO2,MoS2,Charge transport,Hydrothermal processing,Dye sensitized solar cells
更新于2025-09-12 10:27:22
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Mobility of charge carriers in self-assembled monolayers
摘要： We present a new approach to study charge transport within 2D layers of organic semi-conductors (OSCs) using atomic force microscopy (AFM)-based lithography applied to self-assembled monolayers (SAMs), fabricated from appropriate organothiols. The extent of lateral charge transport was investigated by insulating pre-defined patches within OSC-based SAMs with regions of insulating SAM made from large band gap alkanethiolates. The new method is demonstrated using a phenyl-linked anthracenethiolate (PAT), 4-(anthracene-2-ylethynyl)benzyl thiolate. I–V characteristics of differently shaped PAT-islands were measured using the AFM tip as a top electrode. We were able to determine a relationship between island size and electrical conductivity, and from this dependence, we could obtain information on the lateral charge transport and charge carrier mobility within the thin OSC layers. Our study demonstrates that AFM nanografting of appropriately functionalized OSC molecules provides a suitable method to determine intrinsic mobilities of charge carriers in OSC thin films. In particular, this method is rather insensitive with regard to influence of grain boundaries and other defects, which hamper the application of conventional methods for the determination of mobilities in macroscopic samples.
关键词： organic semiconductor,self-assembled monolayer,lateral charge transport,nanografting,conducting atomic force microscopy
更新于2025-09-12 10:27:22
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Charge Transport between Coaxial Polymer Nanorods and Grafted All-Inorganic Perovskite Nanocrystals for Hybrid Organic Solar Cells with Enhanced Photoconversion Efficiency
摘要： The versatile optoelectronics properties of perovskite nanocrystals (NCs) have provided a strong surge for their utilization in different classes of solar cells, organic photovoltaic (OPV) systems being no exception. In an unprecedented approach, a hybrid solar cell with CsPbBr1.5I1.5 NCs strategically grafted on poly(3-hexylthiophene-2,5-diyl) (P3HT) nanorods (NRs) is shown to have a photoconversion efficiency (PCE) of 9.72 ± 0.4 %, with only 1.5 wt% NCs. The improvement is twice more than the P3HT:PCBM reference devices (4.09 ± 0.2 %). The choice of NC composition is validated by Density Functional Theory (DFT) calculations which show decent charge carrier mobility in CsPbBr1.5I1.5, besides having better stability than CsPbI3, making CsPbBr1.5I1.5 NCs suitable contender for hybrid device architecture. A trivial blending of the NCs in P3HT:PCBM matrix results in their non-uniform distribution, escalating charge carrier trapping, albeit maintaining a device efficiency of 8.07 ± 0.3 % with 1 wt% NCs. Uniform NC grafting is propitious over inhomogeneous blending since CsPbBr1.5I1.5 NCs not only act as additional light harvesters, but their chemical grafting onto the P3HT NRs improves the charge transport by creating better charge percolation pathways. The higher crystallinity of the P3HT NRs than P3HT also helps in reducing the trap states.
关键词： P3HT nanorods,charge transport,perovskite nanocrystals,photoconversion efficiency,hybrid solar cells
更新于2025-09-12 10:27:22
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Charge transfer improvement of ZnO-based dye-sensitized solar cells modified with graphite nanosheets and bilayer photoelectrode structures
摘要： In this work, dye-sensitized solar cells (DSSCs) were fabricated with different photoelectrode structures consisting of a ZnO-based photoelectrode, a ZnO/Au Schottky barrier-based photoelectrode, graphite nanosheets loaded on a ZnO (GZnO)-based photoelectrode, graphite nanosheets loaded on a ZnO nanoparticles (GZnO NPs)-based photoelectrode and graphite nanosheets loaded on a ZnO nanoparticles/ZnO (GZnO NPs/ZnO) as a bilayer-based photoelectrode. The photovoltaic characteristics of DSSCs were investigated based on: the power conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage and fill factor. The kinetics electron transport of impedance spectros- DSSCs was carried out using electrochemical copy (EIS). The semi-circle in the Nyquist plot was calculated to rep- resent the charge transfer resistance (Rct). It was found that the GZnO NPs/ZnO bilayer-based photoelectrode exhibited the max- imum Jsc (9.185 mA/cm2) and maximum PCE (2.37%), which resulted by the minimum Rct in the device. The result can be interpreted as showing that a graphite nanosheet structure improves the electron transport property which produces an excellent charge transfer mechanism in the photoelectrode. Accordingly, enhanced perform- ance of ZnO-based dye-sensitized solar cells with graphite nano- sheets loaded on a ZnO nanoparticles layer could be simply explained in terms of the charge transfer mechanism.
关键词： graphite nanosheets,ZnO,dye-sensitized solar cells,charge transport
更新于2025-09-12 10:27:22
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Interfacial Engineering in Functional Materials for Dye‐Sensitized Solar Cells || Binary Semiconductor Metal Oxide as Photoanodes
摘要： As both natural and synthetic metal oxide semiconductors (MOSs) have diverse applications and the properties of MOS can be tailored in many ways, viz., varied choice of morphologies, introducing oxygen vacancies, doping. In photovoltaics, MOSs serve as a scaffold layer for loading dyes in dye-sensitized solar cells (DSSCs) and organic–inorganic hybrid perovskites in perovskite solar cells (PSCs), as well as electron and hole transport layers in DSSCs and organic solar cells (OSCs). The function of scaffold in DSSCs is to facilitate charge separation and charge transport, whereas that of the transport layers is to conduct one type of charge carrier block to the other type. Therefore, tailoring their properties is inevitable to develop high-performing photovoltaic devices using them. On the other hand, the electrochemical properties of the MOS such as band edge energies determine their success as photocatalysts [1].
关键词： metal oxide semiconductors,perovskite solar cells,photovoltaics,charge transport,dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Bromination of the Small-Molecule Acceptor with Fixed Position for High-Performance Solar Cells
摘要： Brominated A?D?A-type small-molecule acceptor ITIC-2Br-γ with certain molecular structure was designed and synthesized. Compared to the mixture of three isomers (ITIC-2Br-m), ITIC-2Br-γ shows stronger absorption in the region of 600?800 nm, which is beneficial to afford higher JSC. Furthermore, single-crystal structure analysis of ITIC-2Br-γ indicates that although the bromine atom has a larger size, the end groups of adjacent molecules still exhibit strong interactions with short π?π distance of 3.28 ?. Because of the Br···S and O···S interactions, all molecules form an interpenetrated three-dimensional network, which is beneficial for the charge to transport along multidirections. The organic solar cells (OSCs) based on the PBDB-T-2F:ITIC-2Br-γ blend film exhibit a higher power conversion efficiency (PCE) of 12.05% due to its better film morphology and higher charge mobilities, whereas a PBDB-T-2F:ITIC-2Br-m-based device only shows a moderate PCE of 10.88%. These results indicate that separation and purification of the brominated A?D?A-type small molecules are an effective way to further improve their photovoltaic performances. Furthermore, bromination is easily synthesized and is of low-cost, which exhibits great potential for the preparation of large-scale OSCs.
关键词： Brominated A?D?A-type small-molecule acceptor,ITIC-2Br-γ,organic solar cells,power conversion efficiency,charge transport
更新于2025-09-12 10:27:22
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Elucidating the effects of guest-host energy level alignment on charge transport in phosphorescent OLEDs
摘要： The correct choice of guest and host molecules in the light-emitting layer is essential for developing high performance phosphorescent organic light emitting devices. However, the effects of the energy level alignment between the guest and the host are yet to be fully elucidated. In this Letter, we use kinetic Monte Carlo simulations to investigate guest-host systems in which the energy gap of the guest and host is fixed, and only the relative energies of the ionization potential/electron affinity are changed to elucidate their effect on charge transport. It was determined that the mobility balance in the blend was sensitive to the energy level alignment, allowing balanced active layer mobility to be achieved despite the hole and electron mobilities being different by around one order of magnitude. It was also found that the mobility of the faster carrier was more sensitive to the energy level alignment than that of the slower carrier due to reduced slower carrier thermalization under deep charge trapping on the guest.
关键词： guest-host energy level alignment,phosphorescent OLEDs,kinetic Monte Carlo simulations,charge transport
更新于2025-09-12 10:27:22
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Graphite-N doped graphene quantum dots as semiconductor additive in perovskite solar cells
摘要： Efficient charge transport is especially important for achieving high performance of perovskite solar cells (PSCs). Here, molecularly designed graphite-nitrogen doped graphene quantum dots (GN-GQDs) act as functional semiconductor additive in perovskite film. GN-GQDs with abundant N active sites participate in the crystallization of perovskite film and effectively passivate the grain boundary (GB) trap states by Lewis base-acid interaction. Moreover, the semiconductive GN-GQDs at GBs exhibit matched energy structure with the perovskite, which facilitate the charge transport at GBs. GN-GQDs also show n-type dopant property to upshift the Fermi energy level of perovskite films. It largely improves the charge transport in PSCs and reduces the interface recombination at the same time. Profiting from these advantages, inverted planar PSCs with NiO/perovskite/PCBM/BCP structure achieves high efficiency of 19.8% with no hysteresis phenomenon. GN-GQDs modified PSCs also show high stability even without encapsulation, benefiting from the protected GBs and more hydrophobic surface of the modified film. This work highlights a judicious design method of GQDs additive to satisfy efficient and stable PSCs.
关键词： N doping,energy structure,graphene quantum dots,perovskite solar cells,charge transport
更新于2025-09-12 10:27:22
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Covalently linked donor–acceptor dyad for efficient single material organic solar cells
摘要： A novel covalently linked donor–acceptor dyad comprising a dithienopyrrol-based oligomeric donor and a fullerene acceptor was synthesized and characterized. The concomitant effect of favorable optoelectronic properties, energy levels of the frontier orbitals, and ambipolar charge transport enabled the application of the dyad in simplified solution-processed single material organic solar cells reaching a power conversion efficiency of 3.4%.
关键词： donor–acceptor dyad,organic solar cells,ambipolar charge transport,solution-processed,power conversion efficiency
更新于2025-09-12 10:27:22
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Strontium Chloride Passivated Perovskite Thin Films for Efficient Solar Cells with Power Conversion Efficiency over 21% and Superior Stability
摘要： Industrialization of perovskite solar cells (PSCs) is constrained by adverse stability in the air. Herein, we report an effective strontium chloride (SrCl2) passivation upon the HC(NH2)2-CH3NH3 (FA-MA) based perovskite thin films for the suppression of non-radiative recombination. Moreover, the recombination dynamics, crystallinity, carrier transport, morphology and the elemental stoichiometry of this film were systematically studied. By optimizing the concentration of SrCl2, the corresponding devices exhibited an increased open-circuit voltage (1.00 V vs 1.09 V), in consistent with the enhanced photoluminescence lifetime. The champion passivated device showed a ascendant power conversion efficiency (PCE) about 21.11% , with over 90% retention of the primal PCE in dry air after 1000 h aging with 20% ~ 30% humidity. A superior stability and an accelerated eletron/hole extraction ability were futher observed by time-resolved photoluminescence (TRPL) spectroscopy.
关键词： Charge-transport,High-performance,Spin coating,Crystallzation,Hysteresis,Ion migration
更新于2025-09-12 10:27:22